The present invention relates generally to systems used to clean sub-surface electrical enclosures, such as the type that house transformers. More particularly, the invention concerns an apparatus with a novel tank and valve system that can be used to clean the sub-surface electrical enclosures without having to de-energize the electrical equipment in the enclosure.
The sub-surface electrical enclosures can be concrete, fiberglass, plywood, etc. Most enclosures have a gravel base although some have a concrete base. Typically the enclosure is 40 inches in diameter and up to 7 feet deep. The enclosure may house one of any number of different pieces of equipment, such as transformers, switchers, relays, interrupters, J-boxes, terminal connections, splice boxes, etc. along with a mass of stiff, high voltage cables. All of these are many different sizes.
In the case of a transformer, there generally is only about 6 to 8 inches of clearance between the transformer and the enclosure wall. There is usually 6 to 12 cables winding around the transformer so there is very limited space in the enclosure. The limited space is for air cooling the transformer. Typically, debris, mud, water, etc. drain into the enclosure and become compacted and wedged in the enclosure.
With the prior art method of de-energizing and removing the equipment from the enclosure then flooding the enclosure with thousands of gallons of water and removing the debris and water with a huge vacuum truck, it is too expensive and labor intensive to do normal maintenance clean-up of the enclosures. However, the water, dirt, debris, etc. around the electrical equipment (e.g., a transformer) can cause contamination of the equipment, rusting, cable deterioration, overheating, etc. all leading to failure of the equipment. If a transformer fails it can leak hazardous materials into the enclosure. The normal life expectancy for example a transformer is 20-30 years. However, it is common for a transformer to fail in five or ten years due to overheating and/or corrosion caused by the water, dirt, debris, etc. As a result, the whole life cycle of the initial investment in the equipment can not be realized.
After a failure has occurred, on average, it requires six to twelve hours depending on the enclosure to remove the failed equipment, clean the enclosure, and connect the new equipment. The labor and equipment costs for such a job can run into the tens of thousands of dollars. As well as, the inconvenience to the customer and the losses in revenue from the customer. Therefore, it would be desirable to have an apparatus that could do regular maintenance on sub-surface electrical enclosure without having to de-energize and/or remove the electrical equipment.